It is known to provide a vehicular exterior rearview mirror assembly that has a mirror head having a mirror casing that is adjustable relative to a mirror mounting portion at the side of the vehicle to which the mirror assembly is mounted. The mirror assembly may comprise a powerfold assembly where the mirror head is adjusted or pivoted relative to the vehicle via an actuator disposed at the mirror mounting portion and/or mirror head. Examples of adjustable or powerfold rearview mirror assemblies and actuators are described in U.S. Pat. Nos. 7,314,285; 7,267,449; 7,159,992; 7,093,946; 6,312,135; 6,243,218 and 5,703,731, which are hereby incorporated herein by reference in their entireties. As the size and/or electrical content of exterior rearview mirror assemblies is increased (such as for pickup trucks and the like), the weight of the mirror head portion likewise is increased, and a larger actuator motor or multiple gears or gear elements are required to provide sufficient torque output to pivot the mirror head via an actuator motor, with such multiple gears adding to the cost and complexity of the actuator assemblies.